The present invention relates generally to the field of display systems and more specifically to large screen displays for presenting images to a number of viewers. More particularly, this invention provides for a large screen display system having the capability of operating in real-time at high resolution rates to provide a three-dimensional image of video information. Still more specifically, the present invention provides for the use of liquid crystal light valves to produce very bright stereoscopic three-dimensional images in a large screen format with computer control and computer image generation, in real time.
Stereoscopic imaging capability can be an important enhancement to displays which portary data containing altitude, distance and ocean depth information in conjunction with other inter-related operational parameters. The provision of such a display which has the ability to display the above types of information interactively in a real-time video format would greatly enhance the perception of such information.
The stereoscopic imaging process has two fundamental requirements. First, two distinct and different images must be presented to the viewer, each of which presents the scene from the view point of one of the viewer's eyes. Next, the system must be able to assure that each eye sees only the one view intended for it, that is, the images must be separated, one to each eye.
Four methods have been used for performing stereoscopic image separation:
(1) Optical separation using lenses, prisms, mirrors, etc.; PA1 (2) Color separation (anaglyphs); PA1 (3) Temporal separation (using shutters, etc.); and PA1 (4) Polarization separation (using polaroid filters).
Of these, the one most amenable to large screen projection systems is the polarization technique. Optical separation requires bulky, often elaborate optical apparatus between the screen and the observer to separate the images. Color separation relies upon encoding the left and right images such that left eye and right eye images are portrayed in colors and such that the viewer sees two different color images. This makes it difficult to portray full color images, produces eye fatigue through "color bombardment" in the viewer which desensitizes the visual system to the colors involved and creates problems for ambient viewing. Temperal separation requires the viewer to wear glasses which are connected to the video system by an umbilical cord and often is accompanied by high voltages in the eyeglasses themselves. The polarization technique, on the other hand, requires only that the two images be projected with orthogonal polarizations, and that the viewer wear a simple pair of polaroid glasses whose polarization axes are arranged at right angles to one another.
Previous stereoscopic imaging techniques that have utilized polarization include those that use two parallel film channels as is depicted in FIG. 1, those using two separate video monitors as is depicted in FIG. 2 and those using projectors with rotating polaroids as is depicted in FIG. 3. The projection techniques most commonly used utilize film, as illustrated in FIG. 1. Parallel optical systems are used to project the two images of the stereo pair. Since film is used, this technique is not useable in video or real time, computer-generated applications. In FIG. 2, two video monitors are arranged at right angles. Each monitor displays one image of the stereo pair. The images are then polarized by filters, combined using a large beamsplitter, and viewed with polarized glasses. This technique is bulky, difficult to align, and is not useable in large screen applications. FIG. 3 shows a system that incorporates the EIDOPHOR projector for large screen presentation. Polarization is induced by a rotating polaroid wheel, which has adjacent sectors polarized at right angles. The video information is synchronized with this rotating wheel, right and left eye views being alternated on the screen. These are in viewed with polaroid glasses. While video can be displayed on this system, it requires a rotating mechanical device that is subject to mechanical failure, has questionable image separation (particularly at the intersections of the polaroid sectors), and requires extensive synchronizing electronics and motors to ensure the proper phasing of the displayed images with the rotating wheel.